 (defmacro HDR-PRAGMA-N            [] "pragma"                       )
 (defmacro HDR-PRAGMA-V            [] "no-cache"                     )
 (defmacro RSC-HTTP-200-OK         [] 200                            )
+
+; Response data names.
+(defmacro DAT-HOSTNAME-N [] "hostname")
+(defmacro DAT-ADDRESS-N  [] "address" )
+(defmacro DAT-VERSION-N  [] "version" )
+(defmacro DAT-VERSION-V  [] "IPv"     )
 
 ; Daemon name, version, and copyright banners.
 (defmacro DMN-NAME        [] "DNS Resolver Daemon (dnsresolvd)"       )

(defmacro DIGITS           [] #"\d+")
(defmacro PARAMS-SEPS      [] #"=|&")

; Common error messages.
(defmacro ERR-PREFIX                    [] "error"                        )
(defmacro ERR-PORT-MUST-BE-POSITIVE-INT [](str ": <port_number> must be "

                                               "Exiting..."              ))
(defmacro ERR-SRV-PORT-IS-IN-USE        [](str "due to the port requested "
                                               "is in use. Exiting..."   ))
(defmacro ERR-COULD-NOT-LOOKUP          [] "could not lookup hostname"    )

; Print this error message when there are no any args passed.
(defmacro ERR-MUST-BE-ONE-TWO-ARGS-1 [](str ": There must be one or two args "
